11:30-11:55 Development and Characterization of a Novel AR -TIF2 Protein-Protein Interaction Biosensor HCS Assay to Measure Co-Activator Recruitment Interactions
Paul A. Johnston, Ph.D., Research Associate Professor, Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine
The AR-TIF2 protein-protein interaction biosensor (PPIB) was developed to measure the interactions between the p160 steroid receptor coactivators (SRC) with nuclear hormone receptors (NRs). Researchers at Cellumen Inc. have generated recombinant adenovirus (R-AV) constructs of the nuclear anchored Transcription Initiation Factor-2 (TIF2-GFP) and the nuclear-cytoplasmic Androgen receptor (AR-RFP) shuttling components of the PPIB. We have characterized the responses of the AR-TIF2 PPIB to androgens and developed a HCS assay that is sufficiently robust and reproducible to be compatible with screening large compound libraries. We have utilized the AR-TIF2 PPIB to characterize and quantify the phenotypes of AR anti-androgens (Biclautamide & Flutamide) that have been used in the clinic to treat prostate cancer. We have also characterized and quantified the phenotype produced by the Hsp90 ATPase inhibitor 17-AAG.
11:55-12:20 Structure-Guided Improvements to
Mark Rizzo, Ph.D., Assistant Professor, Department of Physiology, University of Maryland School of Medicine
A full complement of colors for genetically-encoded fluorescent proteins has nearly been achieved. However, the far majority of these proteins are less than ideal probes for live cell microscopy because of problems with overall brightness when observed with existing imaging technology. Limited brightness, and in particular, low quantum yields are particularly important for cyan fluorescent proteins because they are widely used as donors in Förster resonance energy transfer (FRET) assays and energy transfer efficiency is directly related to the donor quantum yield. To improve the quantum yield of Cerulean fluorescent protein, we used site-directed mutagenesis to optimize residues surrounding the chromophore. This new variant, mCerulean2, has a greatly improved quantum yield of 0.78, is 50% brighter than mCerulean in cells, and is a superior donor for FRET experiments. In an in vitro assay, FRET with mCerulean2: mVenus can be detected with 7.5-fold less protein than for mCerulean. With increased brightness and performance for FRET experiments, mCerulean2 is well suited for FRET experiments in living cells.
12:20-12:45 Multidimensional Fluorescence Imaging for Cell Biology, High-Content Analysis and Label-Free Tissue Analysis
Sunil Kumar, Ph.D., Research Associate, Photonics Group, Physics Department, Imperial College London
This talk will review our development and application of multidimensional fluorescence imaging (MDFI) technology, with an emphasis on fluorescence lifetime imaging (FLIM), implemented in microscopy, endoscopy and tomography. Applied to autofluorescence, MDFI can provide label-free molecular contrast in biological tissue for ex vivo and in vivo applications. For cell biology, high speed FLIM can be used to image the spatio-temporal organisation of proteins and their interactions, including via FRET, for which we are working to improve the imaging speed and spatial resolution. For high content analysis, we have developed an automated high-speed optically-sectioned FLIM multiwell plate reader applicable to fixed and live cells. We have also developed a multiplexed FRET microscope capable of simultaneously imaging two different protein-protein interactions in a cell signalling network. For 3-D imaging of embryos and small organisms, we have developed a FLIM optical projection tomography (OPT) system and are working towards tomographic FLIM and FRET of cleared samples and of live animals for dynamic studies in vivo.
12:45-1:10 Controlling the Signaling Dynamics of Rho GTPases and Cell Motility Using Genetically Encoded Photoactivatable Proteins
Yi Wu, Ph.D., Assistant Professor, Department of Pharmacology, University of North Carolina
For many highly dynamic cell behaviors such as cell migration, signaling occurs transiently at specific locations, with subsecond and submicron precision. Study of such rapid dynamics has been hindered by our inability to manipulate protein activities with precise spatio-temporal control in living cells and animals. Here we describe the engineering of several genetically-encoded photoactivatable Rho GTPases using a light-responsive protein domain (LOV) derived from plant phototropin, enabling reversible and repeatable control of cell signaling in living systems.
11:30-11:55 High-Content Screen for Compounds that Modulate Misfolded Protein Aggregation in C. elegans
Stephen Pak, Ph.D., Research Assistant Professor, Pediatrics, University of Pittsburgh
C. elegans is a powerful genetic organism useful for the study of human diseases. Recently, we developed a C. elegans model of a human misfolded protein accumulation disorder, a1-antitrypsin-deficiency. To facilitate the identification of therapeutic compounds, we developed a fully automated, whole organism-based assay for the high content screening of small molecules. Initial screens identified hit compounds that significantly reduce the accumulation of protein aggregates. Characterization of these compounds should provide valuable insight into pathways responsible for the disposition of protein aggregates. These results demonstrate the utility of C. elegans in drug discovery and provide a stepping-stone for future C. elegans-based drug screens.
11:55-12:20 Quantitation of Fibroblast Growth Factor (FGF) Signaling by High-Content Analysis in Transgenic Zebrafish
Andreas Vogt, Ph.D., Research Assistant Professor, Pharmacology, University of Pittsburgh
The zebrafish is one of few multicellular organisms compatible with compound screening in multiwell plates. The zebrafish embryo is particularly suited for image based screens due to its small size and optical transparency. We have developed an image analysis method to quantify activation of fibroblast growth factor (FGF) signaling in a transgenic zebrafish reporter line that expresses green fluorescent protein (GFP) in particular regions of the brain. The system delivers graded responses and quantified the activity of a novel small molecule inhibitor of the dual specificity phosphatase DUSP6 (MKP-3).
12:20-12:45 High-Content Imaging Approaches to Interrogate in vitro and in vivo Tumor Angiogenesis
Mark Uhlik, Ph.D., Senior Research Scientist, Angiogenesis & Tumor Microenvironment DHT, Eli Lilly & Co.
Solid tumors require the development of new blood vessels via angiogenesis for their continued growth and metastasis. Tumor angiogenesis is a complex biological process involving multiple cell types, soluble factors, microenvironmental cues, and cell-cell interactions. In order to enable the discovery of anti-angiogenic compounds that interfere with these biological processes we are pursuing a phenotypic drug discovery approach driven predominately by cell-based high-content assays. This high-content-enabled paradigm of phenotypic drug discovery provides an avenue to 1) identify compounds that modulate molecular targets from a variety of functional classes, 2) identify compounds that modulate pathways not previously identified as having roles in angiogenesis, 3) screen compounds in complex biological systems composed of multiple cell types, and 4) recognize and filter out compounds that may be overtly cytotoxic. Using an endothelial/mesenchymal stem cell co-culture model of cord formation and assays to assess endothelial migration, proliferation, and apoptosis we are able to bin compounds into discrete phenotypic activity classes. Compounds are further tested in tumor xenograft models for in vivo angiogenesis and tumor growth properties using quantitative multiplexed fluorescence tissue imaging.
12:45-1:10 From Cilia to Schistosomes: High-Content Analysis for Unusual Targets
Michelle Arkin, Ph.D., Assistant Adjunct Professor, Pharmaceutical Chemistry, University of California, San Francisco
In the academic screening environment, one often encounters novel and complex targets including whole organisms, parasites and organelles. High-content analysis has been a versatile high-throughput screening tool for a wide range of academic applications. For instance, to find mediators of sonic hedgehog-dependent Smoothened signaling, we have developed an image-based method that measures YFP-tagged Smoothened protein translocation in the cilia of murine renal cells. Our neglected disease research is aimed at finding novel anti-parasitic drugs. Using a single nuclear stain and size-based discrimination of parasite and human host nuclei, we can quickly identify selective inhibitors of intracellular Trypanosoma cruzi, the causative agent of Chagas disease. We have also been developing high-throughput screening approaches for anti-parasitics that target schistosomula, the immature worms that cause schistosomiasis. These and related projects showcase innovative drug-discovery approaches to unique and challenging targets from academia.